Part 7 (1/2)
=Operation of Special Crankshaft Lathe=--The total equip 27) is carried on a three-tool turret tool-block Thea crankshaft is as follows: A round-nosed turning tool is first fed into a cross stop as illustrated in the plan view at _A_, which gives the proper diaed and the tool feeds across the pin until the autoes the first stop, which throws out the feed autoainst a positive stop by means of the handwheel The roller back-rest is next adjusted against the work by the cross-feed handwheel operating through a telescopic screw, and the filleting tools are brought into position as at _B_ These are run in against a stop, re the pin the proper width and fillets of the correct radius If the crankshaft has straight hichthe webs to the correct width During these last two operations, the crank is supported by the roller back-rest, thus eli
[Illustration: Fig 28 (A) Spherical Turning with Co]
After one pin is finished in the manner described, the back-rest is moved out of the way, the autoe shi+fted to the next pin, and the operation repeated The tools are held in position on the turret by studs, and they can be moved and other tools quickly substituted for pins of different widths Thisthe pins close to the required size, the finishi+ng operation being done in a grinder It should be , that ricultural round fro=--Occasionally it may be necessary to turn a spherical surface in the lathe Sketch _A_, Fig 28, sho a small ball-shaped end can be turned on a piece held in a chuck The lathe carriage is adjusted so that the pin around which the compound rest swivels is directly under the center a The bolts which hold the swivel are slightly loosened to allow the top slide to be turned, as indicated by the dotted lines; this causes the tool point to move in an arc about center _a_, and a spherical surface is turned Light cuts must be taken as otherwise it would be difficult to turn the slide around by hand
[Illustration: Fig 29 Spherical Turning Attachine Lathe]
Sketch _B_ illustrates how a concave surface can be turned The cross-slide is adjusted until swivel pin is in line with the lathe centers, and the carriage isthe bed until the horizontal distance between center _b_ of the swivel, and the face of the work, equals the desired radius of the concave surface The turning is then done by swinging the compound rest as indicated by the dotted lines The slide can be turnedthe tailstock center to force it around A projecting bar is clamped across the end of the slide at _d_, to act as a lever, and a centered bar is placed between this lever and the tailstock center; then by screwing out the tailstock spindle, the slide is turned about pivot _b_ The alignment between the swivel pin and the lathe centers can be tested by taking a trial cut; if the swivel pin is too far forward, the tool will not touch the turned surface if moved past center _c_, and if the pin is too far back, the tool will cut in on the rear side
=Spherical Turning Attach must be done repeatedly, special attach 29 shows an attach the spherical ends of ball-and-socket joints The height or radius of the cutting tool and, consequently, the dia screw _A_ The tool is swung around in an arc, by turning handle _B_ which revolves a wor with an enclosed heel As will be seen, the work is held in a special chuck, owing to its irregular shape
[Illustration: Fig 30 Attachine Piston]
Another spherical turning attach the ends of gasoline engine pistons The cross-slide has bolted to it a bar _A_ carrying a roller which is pressed against a for plate _B_, which is attached to a cross-piece fastened to the ways of the lathe bed, is curved to correspond with the radius required on the piston end, and when the tool is fed laterally bythe cross-slide, it follows the curve of plate _B_ The piston is held in a special hollow chuck which locates it in a central position and holds it rigidly
In connection with lathe work, special attachments and tools are often used, especially when considerable work of one class e quantities, it is usually more econo ned for repetition work
=Turning with Front and Rear Tools=--In ordinary engine lathe practice, one tool is used at a time, but some lathes are equipped with tool-holders at the front and rear of the carriage so that two tools can be used si 31 shows a detail view of a lathe in which front and rear tools are being used These tools are of the inserted cutter type and the one at the rear is inverted, as the rotary movement of the work is, of course, upward on the rear side This particular lathe was designed for taking heavy roughing cuts and has considerable driving power
[Illustration: Fig 31 Front and Rear Tools used for Roughing]
The part shown in this illustration is a chrohed out to for machine spindle It is necessary to reduce the diath of 27 inches, because of a collar on one end This reduction is e of the two tools, with a feed of 1/32 inch per revolution and a speed of 60 revolutions percuts is desirable, especially when the parts are required in large quantities, because the thrust of the cut on one side, which tends to deflect the work, is counteracted by the thrust on the opposite side
[Illustration: Fig 32 Lo-swing Lathe for Multiple Turning]
Sometimes special tool-holders are made for the lathe, so thatdifferent surfaces or dia set in the proper relation to each other The advantage of this n of a special lathe for
=A Multiple-tool Lathe=--The lathe shown in Fig 32 (which is built by the Fitchburg Machine Works and is known as the Lo-swing) is designed especially for turning shafts, pins and forgings not exceeding 3-1/2 inches in diaes _A_ and _B_ which, in conjunction with special tool-holders, make it possible to turn several different diameters simultaneously At the front of this lathe there is an auto the feed when the tools have turned a surface to the required length This stop-rod carries adjustable stops _D_ which are set to correspond with shoulders, etc, on the work The rod itself is also adjustable axially, so that the tools, which are usually arranged in groups of two or ed at a point nearer or farther fro to a variation in the depth of center holes For exaroup of tools farther toward the headstock after they had been autoed, the entire rod with its stops would be adjusted the required a 33 Lo-swing Lathe arranged for Turning a Steering Knuckle]
The gage _G_, which is attached to a swinging arm, is used to set the stop bar with reference to a shoulder near the end of the work, when it is necessary to finish other parts to a given distance froe will be explainedlubricant for the tools is supplied through the tubes _E_ The lathe shown in the illustration is arranged for turning Krupp steel bars A rough bar and also one that has been turned ht The plain cylindrical bar is turned to five different diaes
[Illustration: Fig 34 Plan Vieing Method of driving Steering Knuckle and Arranges 33 and 34 sho a Lo-swing lathe is used for turning the steering knuckle of an automobile Four tools are used in this case, three cylindrical surfaces and one tapering surface being turned at the same tie The taper part is turned by the second tool from the headstock, which is caused to feed outward as the carriage advances by a taper attachainst a templet at the rear, which is tapered to correspond with the taper to be turned This templet is attached to a bar which, in turn, is fastened to a stationary bracket seen to the extre 33 This part is finished in two operations, the tool setting being identical for each operation, except for diameter adjustments As the illustrations show, three of the four tools e on different diameters, while the fourth finishes the taper
These pieces, which are rough drop forgings, are first reduced to the approxirind the tools, they are reset and those parts which have been roughed out are turned to the finished size The average ti, turning and replacing the piece, is one minute, while for the second operation with the finer feed, an average time of two minutes is required The work is driven by sleeve _S_, which fits over the spindle and is held in position by the regular driver, as shown This sleeve is notched to fit the knuckle, so that the latter can easily and quickly be replaced when finished
One of the interesting features of this job lies in thethe shoulders on each knuckle, at the same distance from the hole _H_ which is drilled previously, and which receives the bolt on which the knuckle swivels when assembled in a car As soon as the knuckle has been placed between the centers, a close-fitting plug _P_ (Fig 33) is inserted in this hole and the indicator ar up to the position shown The stop-rod on which the stops have been previously set for the correct distance between the shoulders is next adjusted axially until the gage _G_ just touches the plug _P_ The indicator is then swung out of the way, and the piece turned If the next knuckle were centered, say, deeper than the previous one which would, of course, cause it to be located nearer the headstock, obviously all the shoulders would be located farther from the finished hole, provided the position of the stops remained the same as before In such a case their position would, however, be changed by shi+fting the stop-rod until the gage _G_ again touched the plug thus locating all the stops with reference to the hole
As the adjustes the position of the taper templet as well as the stops, it is evident that both the shoulders and the taper are finished the same distance from the hole in each case The connection of the bracket (to which the templet ar 33 This bracket can either be locked to the ways or adjusted to slide when the stop-rod is35 First and Second Operations on Auto Lathe]
The part illustrated in Fig 35 is an automobile trans and spherical surfaces are turned The upper vies, diagraement of the tools and work for the first operation After the shaft is ”spotted” at _A_ for the steadyrest, the straight part _C_ and the collar _B_ are sized with tools _S_ and _R_ which are roove is then cut in collar _B_ by tool _R_, after which spherical end _D_ is fore This attach attachment, the substitution of a circular te the only practical difference